Here is a comprehensive list of beep codes: BEEP CODES
Just from my memory (which isn't the best in the world), I think your beep code has something to do with the video card area. My first question would be if you have the sli configured correctly (don't know this particular board, but familar with the A8N-sli deluxe) in the bios.
Otherwise, do you have your single video card in the proper slot for one card?
Second question would be if you have the Bios configured correctly for a single card?
Do you have the pci power lead(s) connected to the video card?
Do you have the (my A8N-sli deluxe does have that feature) the EZ plug connected to the motherboard to boost power to the video area? (this is in addition to the molex connector)
Again, you need to check to make sure what the beep codes says, but off the top of my head, I think it is video related, but no promises.
As an added concern, an Ultra is not a great power supply and it might (it is iffy) not be supplying enough power for an 8800 video card.